The present invention relates to an apparatus for feeding sheet articles and, more particularly, to an apparatus applicable to a mail processing system for temporarily accumulating postcards and letters which come in the apparatus arbitrarily either one at a time or together with others and sending them out in a steady flow at predetermined intervals.
A apparatus of the type described customarily includes an upstream transport path for driving sheet articles such as mail articles into a feeder section, a suction chamber communicated to a vacuum pump by a hose for sucking the articles arrived in the feeder section, a suction belt provided with a number of holes which are communicatable to the suction chamber, a reverse roller rotatable in the opposite direction to the intended direction of article transport, a reverse belt wound around the reverse roller, a base belt for supporting the bottom edges of the articles, a detection lever for detecting the volume of articles sequentially accumulated, a microswitch actuated by the detection lever, and a downstream transport path for driving the articles sucked by the suction belt to the subsequent processing stage. Articles coming in arbitrarily through the upper transport path either in a bunch or at intervals are conveyed by the base belt in the direction of feed until their leading edges abut against the reverse belt, the articles being accumulated in an upright position.
A problem with such a prior art apparatus is that three or more articles are apt to be fed at the same time by the suction belt due to disorderly accumulation of articles in the feeder section. Although one of those articles which positively abuts against the reverse belt may be forced back into the feeder section, the others are not sufficiently effected by the reverse belt resulting in two or more articles being sent out to the downstream transport path at the same time. Another problem is that the reverse roller bounces when the leading edge of a relatively thick article hits against the reverse belt or when articles of different thicknesses are sent out from the feeder section. Should the reverse belt be brought out of contact with the articles due to the bounce, it would fail to effectively operate and allow a plurality of articles to be fed out at the same time.